Патент USA US2107327код для вставки
Feb. 8, 1938. 2,107,327 T. A. cRElGHToN METHOD FOR CEMENTING WELL CASINGS Filed Oct. l, 1957 il«íëL v PatentediFeb. s, 1938 UNITED STATES ' PATENT OFFICE 2,101,327 l METHOD Fon CEMENTING WELL cAsmGs Thomas A. Creighton, Long Beach, Calif., as signor of one-half to Jesse C. Wright, Los Angeles, Calif. Application October 1, 1937, Serial No. 166,790 9 Claims. (C1. 16B-21) This invention relates to a method useful in well drilling operations and relates more particu larly to a method for cementing casing in a Well. A general object of this invention is to provide a 5 simple, rapid and commercially practical method for cementing casing in a well. In the drilling of deep wells such as oil wells, gas wells, etc. it is usually necessary to line or case the well with a casing to support the wall of the well and to exclude unwanted fluids from the well. It is the common practice to cement the lower portion of the casing in the well to pre vent the contamination of the fluid to be pro duced and to prevent both the upward and down r ward passage of ßuid around the set casing. In the methods now usually employed to cement a casing in a well the casing is run into the well to its ñnal position and cement is then pumped down through the casing,»or through a tube within the casing, to the bottom of the well and is forced up around the lower portion of the casing by the pump pressure. In the rotary method of well drilling the well and the casing are filled with the mud-laden drilling fluid and the cement 05 is contaminated with this drilling fluid when it is pumped through the casing and forced up around the lower end of the casing. As the cement is forced up around the lower end of the casing it mixes with the mud on the casing and on the Wall of the Well and follows the paths of least resistance leaving channels or spaces occupied by mud and other foreign material. This so-called “channeling” of the cement that encases the lower portion of the casing often results in the leakage of water or other unwanted fluid into the well and necessitates expensive and'time consum ing operations to stop». the leakage around the casing. Another object of this invention is to provide 40 a method for cementing a casing in a well that assures a full and eiîective shut-off around the casing. Another object of this invention is to provide a _ method for cementing well casing that avoids the “channeling” of the cement. Another object of this invention is to provide a method for cementing a well casing in which the cement is contaminated by mud, cuttings, 50 etc. to a minimum extent. Another object of this invention is to provide ` a method for cementing a'well casing in which it is unnecessary to pump the cement up around the casing shoe whereby the cement is free to flow at a slower rate and to completely occupy the annular space around the casing to form a tight, effective shut-off. A further object of this invention is to pro vide a method for cementing well casing that is easy to perform and that does not necessitate the Ul employment of expensive equipment. The various objects and features of my in vention will be fully understood from the follow ing detailed description of a typical preferred manner of carrying out the method of the in 10 vention, throughout which description reference is made to the accompanying drawing, in which: Fig. 1 is a longitudinal sectional view of the lower portion of a well illustrating the cement being delivered to the well in accordance with the 15 method of the invention. Fig. 2 is a view similar to Fig. 1 showing the casing about to enter the cement and Fig. 3 is a view similar to Fig. 1 with the lower portion of the casing in vertical cross section and showing the casing set in the 20 cement. In the drawing I have illustrated the open or uncased lower portion of a typical well W. It will be assumed that the well is being drilled by the rotary method and is iilled with the rotary mud M 25 usually employed in the rotary method of drilling. As illustrated in Fig. 1 of the drawing a string of drill pipe P is in the well W and carries at its lower end a drilling tool T. The tool T may have drilled the well W to the desired depth. In ac 30 cordance with the usual practice the well drilling tool 'I' has circulation ports I0 for discharging the drilling fluid or rotary mud M. The method provided by the present invention includes, generally, the passage or delivery of the 35 proper amount of cement Il to the lower portion of the well W through the drill pipe P, the re moval of the drill pipe P and the tool T from the Well, providing a casing C having a closure or a valved shoe S on its lower end and having a 40 suitable float valve V, and then running the cas ing C into the well W to its final position in the well to displace the cement Il upwardly around its lower end wherebyv the lower portion of the casing is embedded in the cement. 45 In accordance with the present invention the drill pipe P may be .employed to deliver or con duct the cement mixture or cement slurry to the bottom of the well W. When the well W has been drilled to the desired depth and while the -drill 50 pipe P remains in the well bore the cement Il may be passed down through the pipe. In prac tice the cement slurry Il is pumped Vthrough the drill pipe P by suitable pumping equipment. The cement I l discharges from the ports I0 of the 55 2 2,107,8‘27 drilling tool T toñow into the lower portion of the well. Thus the cement Il, in the quantity shoe S and the lower portion of the casing enters the cement Il. As described above, the cement previously determined, is delivered to the bottom ' II is retarded so that it remains in a fluid or of ,the well bore W with little or no contamina plastic state until the casing C is embedded in\~it. The valve I4 in the shoe S prevents the cement tion. The drill pipe P conducting the cement _II of course prevents the mud M in -the well W from contaminating the cement II las it is de livered downwardly into the well. \ The character of the cement I I delivered to the 10 lower portion of the well W is of particular im portance to the method of the invention. In ac cordance with the invention Portland cement is employed that is retarded to attain its initial set in from 30 to 40 hours after mixing. When the II from entering the casing C so that the casing displaces the cement II upwardly into the annu lar space X between the casing and the wall of the well W. During the~passage of the casing C into or through the cement -II it is preferred to lower the casing C slowly so that the cement is made to slowly move upwardly around the casing C ln the space X as it is displaced by the slow moving casing. It is believed that it will be 15 required quantity of cement I I has been pumped readily understood how the casing C provided into the'well W through the drill pipe P the drill pipe carrying the tool T is withdrawn from the with the valved shoe S displaces the cement I I to iiow upwardly in the‘space X around the casing. When the casing C is in its ñnal position in the well the cement II is allowed to set and the ce well. It is to be particularly noted that the ce ment II is delivered to the lower portion of the 20 well W in an~ uncontaminated state without the necessity of runninga special cementing string into the well. As .the drill pipe P is already in the well at the start of the cementing operation Vthe employment of the pipe P to conduct the cement effects a marked saving in time. Immediately following the withdrawal of the drill pipe P and the tool T from the well the casing C is assembled and run into the well. The shoe S on the lower end of the casing C is pro 30 vided with means for preventing the entrance of ñuid into the casing when the same is run into 4the well, whereby the casing C may be iloated into the well. In the particular case illustrated in the drawing the shoe S has a cage I2 provided 35 with a valve seat I3 and a ball valve I4 co operates with the seat I3 to close the lower end of the casing C. The valve V may be provided in the casing C to assure that the casing may be floated into the well in the event the valved 40 shoe S leaks. The float valve V may be' of typical construction and is designed to positively pre vent up-ñow in the casing C and to trap or sup port a substantial head of fluid in the casing. 'I'he valve V may be mounted or arranged in one 45 of the couplings I5 of the casing and may be provided at any desired point in the lower por tion of the casing. The valve elements I2, I3 and I4 of the casing shoe S and the iloat valve V are formed of frangible or drlllable material so that they may be readily drilled out when the well is to be completed or deepened. The valve V may be of any typical construction and any suitable form of valved shoe S or closure may bel em ployed on the lower end of the casing C. Ac cordingly, the invention is not to be considered as restricted to the use of the particular/vw 'structures illustrated in the drawimg. The casing C equipped with the valved shoe S and the iloat valve V, as described above, is run 60 into the well W in the usual manner. The valved shoe S and the valve V positively prevent the up-flow of fluid _in the casing C and permit the casing to be floated vinto a deep well without dan ger o1' parting through its own Weight. In float ing the casing C into the well W the valve V and the valved shoe S prevent the entrance of the - mud M tothe casing so that the hollow or empty casing has sutllcient buoyancy to support itself against parting. It may be necessary to pour -mud or other iluid F into the empty casing C to give it sufñcient weight so that it may be run into the well. The casing C may be run through the well to its final position. « During the latter portion of the downward movement of the casing C into the well W the menting operation is complete. It is to be under 20 stood that the valve V, the valve elements I2, I3 and I4 in the shoe S, and any other internal parts of the shoe S may be removed or broken »out to permit the testing of the cement seal and the casing C and to permit completion of deepen 25 ing of the well. The method provided by the present invention for cementing well casing prevents “channeling” of the cement due to pumping of the cement up wardly around the lower end of the casing and 30 thus assures an eiîective iluid tight seal. The method may be readily carried out without em ploying special packers, etc. The cement II is delivered to the lower portion of the well W through the drill pipe P so that it is not con taminated by the mud or iluid M in the well. The lowering of the casing C into the mix or body of plastic cement II in the bottom of the well bore W assures the complete embedding of the lower portion of the casing C in the cement so that ñuid cannot possibly leak or ilow through the an nular space X between the casing and the wall of the well. - Having described only a typical preferred man ner of carrying out the method of my invention, I do not wish to be limited or restricted to the speciñc details herein set forth, but wish to re serve to myself any variations or modifications that may appear to those skilled in the art or fall within the scope of the following claims: Having described my invention, I claim: 1. The method of cementing a casing in a well comprising, depositing a body of plastic cement in the well, and then running the casing into the well to enter it in the cement. 55 2. 'I'he method of cementing a casing in a well comprising passing a body of plastic cement to the lower portion of the well, providing the casing with a. closure at its lower end, and run ning the casing into the well to immerse its lower 60 portion in the plastic cement. `3. 'I'he herein described method comprising depositing a body of plastic cement in a well by passing the cement down through a tubular drill ing string in the well, removing the drilling string 65 from the well, running a casing into the well to introduce its lower end into the cement, and then allowing the cement to set. 4. The well drilling method comprising oper ating a tubular well drilling string in a well, 70 passing plastic cement through the string to the lower portion of the well to occupy the same, re moving the drilling string from the well, lower ing a well casing into the well to introduce the casing into the cement and cause the upward dis 75 2,107,327 placement of the cement around the casing, and then allowing the cement to set. 5. The well drilling method comprising operat ing a tubular well drilling string in a well, pass ing plastic cement through the string to the' lower portion of the Well to occupy the same, removing the drilling string from the well, lowering a cas ing having a closed lower end into the well to enter its lower portion in the cement and there 10 by cause the upward displacement of the cement around the casing, and then permitting the ce ment to set. ' 6. The method of cementing a. casing in a well comprising delivering a mass o! plastic cement to the lower portion of the well, providing a cas ing with a valved lower end, running the casing into the well so that its lower portion enters the cement and 'displaces the cement upwardly around the casing, and then allowing the cement 20 to set. 7. The method of cementing 'a casing in a well comprising delivering a mass of retarded plastic cement to the lower portion of thewell, provid ing a casing with a closed lower end, running the casing into the well so that its lower portion en ters the cement anddisplaces the cement up wardly around the casing, and then allowing the cement to set. 8. The method of cementing a casing in a well comprising, delivering a mass of retarded plas tic cement to the bottom of the well, ñoating a casing into the well to enter the cement and displace the cement upward around the casing and then allowing the cement to set. '9. The well drilling method comprising oper `ating‘a tubular well drilling string in a well, pass- , ing retarded plastic cement through the string to the lower part of the well, removing the drilling string from the well, providing a casing with a valved shoe on its lower end, floating the casing into the well sov that its lower portion enters the cement and displaces the cement upwardly around the casing, lowering the casing to its 20 final position in the well, and then allowing the cement to harden. ` THOMAS A. CREIGHTON.